Fiber/matrix debond growth from fiber break in unidirectional composite with local hexagonal fiber clustering

2016 ◽  
Vol 101 ◽  
pp. 124-131 ◽  
Author(s):  
Linqi Zhuang ◽  
Andrejs Pupurs ◽  
Janis Varna ◽  
Zoubir Ayadi
Keyword(s):  
Unidirectional Composite ◽  
Fiber Break ◽  
Fiber Clustering ◽  
Fiber Matrix

scholarly journals Dynamic effects of single fiber break in unidirectional glass fiber-reinforced composites

2016 ◽  
Vol 51 (9) ◽  
pp. 1307-1320 ◽  
Author(s):  
Raja Ganesh ◽  
Subramani Sockalingam ◽  
Bazle Z (Gama) Haque ◽  
John W Gillespie
Keyword(s):  
High Speed ◽  
Glass Fibers ◽  
Element Model ◽  
Unidirectional Composite ◽  
Stress Concentrations ◽  
Fiber Fracture ◽  
Fiber Break ◽  
Axial Tensile ◽  
Brittle Fiber ◽  
Static Tensile

In a unidirectional composite under static tensile loading, breaking of a fiber is shown to be a locally dynamic process that leads to stress concentrations in the interface, matrix and neighboring fibers that can propagate at high speed over long distances. To gain better understanding of this event, a fiber-level finite element model of a two-dimensional array of S2-glass fibers embedded in an elastic epoxy matrix with interfacial cohesive traction law is developed. The brittle fiber fracture results in release of stored strain energy as a compressive stress wave that propagates along the length of the broken fiber at speeds approaching the axial wave-speed in the fiber (6 km/s). This wave induces an axial tensile wave with a dynamic tensile stress concentration in adjacent fibers that diminishes with distance. Moreover, dynamic interfacial failure is predicted where debonding initiates, propagates and arrests at longer distances than predicted by models that assume quasi-static fiber breakage. In the case of higher strength fibers breaks, unstable debond growth is predicted. A stability criterion to define the threshold fiber break strength is derived based on an energy balance between the release of fiber elastic energy and energy absorption associated with interfacial debonding. A contour map of peak dynamic stress concentrations is generated at various break stresses to quantify the zone-of-influence of dynamic failure. The dynamic results are shown to envelop a much larger volume of the microstructure than the quasi-static results. The implications of dynamic fiber fracture on damage evolution in the composite are discussed.

Growth and Interaction of Debonds in Local Clusters of Fibers in Unidirectional Composites during Transverse Loading

2017 ◽  
Vol 754 ◽  
pp. 63-66 ◽  
Author(s):  
Janis Varna ◽  
Lin Qi Zhuang ◽  
Andrejs Pupurs ◽  
Zoubir Ayadi
Keyword(s):  
Release Rate ◽  
Tensile Loading ◽  
Unidirectional Composite ◽  
Fiber Distribution ◽  
Transverse Loading ◽  
Transverse Tensile ◽  
Fiber Clustering ◽  
Local Clustering ◽  
The Matrix ◽  
Matrix Region

Fiber/matrix debonding in transverse tensile loading of a unidirectional composite is analyzed calculating energy release rate (ERR) for interface crack propagation. Non-uniform fiber distribution (local hexagonal fiber clustering) is assumed in the model. The matrix region containing the central fiber with the debond and the 6 surrounding fibers is embedded in a large block of homogenized composite which has the same fiber content as the region analyzed explicitly. Some of the fibers surrounding the central fiber may also have a debond. The effect of the local clustering and of the presence of other debonds on magnification of the ERR is analyzed.

scholarly journals Generalized locally-exact homogenization theory for evaluation of electric conductivity and resistance of multiphase materials

2020 ◽  
Vol 9 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Guannan Wang ◽  
Qiang Chen ◽  
Mengyuan Gao ◽  
Bo Yang ◽  
David Hui
Keyword(s):  
Electric Fields ◽  
Unidirectional Composite ◽  
Homogenization Theory ◽  
Governing Equations ◽  
Multiphase Materials ◽  
Micromechanics Models ◽  
Present Technique ◽  
Unit Cells ◽  
Electric Behavior ◽  
Fiber Matrix

AbstractThe locally-exact homogenization theory is further extended to investigate the homogenized and localized electric behavior of unidirectional composite and porous materials. Distinct from the classical and numerical micromechanics models, the present technique is advantageous by developing exact analytical solutions of repeating unit cells (RUC) with hexagonal and rhomboid geometries that satisfy the internal governing equations and fiber/matrix interfacial continuities in a point-wise manner. A balanced variational principle is proposed to impose the periodic boundary conditions on mirror faces of an RUC, ensuring rapid convergence of homogenized and localized responses. The present simulations are validated against the generalized Eshelby solution with electric capability and the finite-volume direct averaging micromechanics, where excellent agreements are obtained. Several micromechanical parameters are then tested of their effects on the responses of composites, such as the fiber/matrix ratio and RUC geometry. The efficiency of the theory is also proved and only a few seconds are required to generate a full set of properties and concomitant local electric fields in an uncompiled MATLAB environment. Finally, the related programs may be encapsulated with an input/output (I/O) interface such that even non-professionals can execute the programs without learning the mathematical details.

scholarly journals Acoustic Emission Signal Due to Fiber Break and Fiber Matrix Debonding in Model Composite: A Computational Study

2021 ◽  
Vol 11 (18) ◽  
pp. 8406
Author(s):  
Zeina Hamam ◽  
Nathalie Godin ◽  
Claudio Fusco ◽  
Aurélien Doitrand ◽  
Thomas Monnier
Keyword(s):  
Acoustic Emission ◽  
Computational Study ◽  
Fiber Composite ◽  
Carbon Fiber Composite ◽  
Model Composite ◽  
Fiber Break ◽  
Emission Signal ◽  
Detection And Identification ◽  
Fiber Matrix ◽  
Ae Signals

Acoustic emission monitoring is a useful technique to deal with detection and identification of damage in composite materials. Over the last few years, identification of damage through intelligent signal processing was particularly emphasized. Data-driven models are developed to predict the remaining useful lifetime. Finite elements modeling (FEM) was used to simulate AE signals due to fiber break and fiber/matrix debonding in a model carbon fiber composite and thereby better understand the AE signals and physical phenomena. This paper presents a computational analysis of AE waveforms resulting from fiber break and fiber/matrix debonding. The objective of this research was to compare the AE signals from a validated fiber break simulation to the AE signals obtained from fiber/matrix debonding and fiber break obtained in several media and to discuss the capability to detect and identify each source.

Using Genetic Algorithms to study the Effect of Cellulose Fibers Ratio on the Fiber-Matrix Interface Damage of Biocomposite Materials

2019 ◽  
Vol 12 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Khadidja Atig ◽  
Allel Mokaddem ◽  
Mohamed Meskine ◽  
Bendouma Doumi ◽  
Mohammed Belkheir ◽  
...  
Keyword(s):  
Probabilistic Models ◽  
Cox Model ◽  
Cellulose Fibers ◽  
Unidirectional Composite ◽  
Matrix Interface ◽  
Interface Damage ◽  
Genetic Modeling ◽  
The Matrix ◽  
Fiber Matrix Interface ◽  
Fiber Matrix

Background:In this article, we have studied the effect of cellulose fibers ratio on the fiber matrix interface damage of biocomposite materials based on a Polypropylene (PP) matrix.Methods:Few patents on the effect of cellulose fibers ratio on the fiber-matrix interface damage of biocomposite materials were published. We have investigated this damage, using a metaheuristic simulation based on the two Weibull probabilistic models which successively described the damage of the fiber and the matrix, our objective function is presented by the Cox model.Results:The results of our genetic modeling confirm that the level of damage is related to the mechanical stresses applied to the five studied materials Cotton-Polypropylene, Jute-Polypropylene, Flax- Polypropylene, Ramie-Polypropylene and Aramid-Polypropylene. Our genetic modeling indicates that the rate of cellulose in each fiber has a significant influence on the progressive degradation of the interface. The numerical simulation compared to the result obtained by genetic algorithm for the Aramid- Polypropylene composite shows that the level of degradation of the interface is greater compared to other biocomposite materials and that Cotton-Polypropylene has a very low interface damage compared to other biocomposites (82.5% cellulose).Conclusion:It can thus be said that the model correctly took into account the degradation phenomenon of a unidirectional composite and biocomposite and our calculations coincide perfectly with the conclusions of Antoine et al. who determined that the rate of cellulose in each fiber participates in the improvement of the mechanical properties of biocomposite materials.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

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